1. Brief Description of the Field of the Invention
The present invention relates to an improved rheological composition for organic systems which is in a pumpable or pourable liquid form at ambient temperatures. Such an additive provides improved viscosity control and a variety of other rheological properties to many types of organic systems without adverse environmental and other effects. The present invention also relates to a thickened composition or fluid system containing the new rheological composition.
The present invention particularly relates to novel pumpable or pourable organophilic clay/polyamide compositions which are dispersible in organic or solvent-based (i.e., non-aqueous) fluids to provide improved ease of incorporation and a wide variety of rheological, viscosity and flow control properties to such fluids. Such organic fluids include paints and coatings as well as oil-based drilling fluids, inks and adhesives. The invention also pertains to a process for preparing these novel composition. The invention also includes organic fluids containing such novel compositions as rheological additives.
2. Description of the Prior Art
The art has long investigated and sought chemical materials, referred to as thixotropes, rheological additives, rheological control agents and thickeners, which are used as additives to control the rheological properties of various liquid organic compositions. Examples of commercially significant liquid organic compositions include inks, paints, coatings and drilling fluids for oil well drilling operations. It has been generally conceded that to be effective, especially for paints and coating compositions, such rheological control agents should provide desired and controllable rheological characteristics to the liquid systems in which they are used. In organic paints and coatings, for instance, the thickener can provide viscosity modification, improved stability and pigment suspension, and improved application properties. In this regard, organophilic clays, as discussed hereafter, have been shown to be useful to thicken various organic and solvent-based compositions. Fumed silica and precipitated silica have also been used to thicken certain types of organic compositions.
Organic and solvent-based fluids include organic, solvent and alkyd-based paints, coatings, inks, construction materials, cosmetics, and wood stains utilized in various and numerous aspects of a consumer-based industrial society. Depending on the composition of the fluid systems, the products made with these thickeners can be useful as decorative and protective coatings, including paper coatings, inks, sealants, adhesives, petroleum drilling fluids, completion fluids, and the like.
It has been known since the mid 1940's that organophilic clays, often referred to as organoclays, could be used to provide various rheological properties to a variety of organic liquid compositions. Organophilic clays are modified smectite-type clays prepared by the reaction of an organic cation, usually a quaternary ammonium chloride compound, with a smectite-type clay utilizing various processes now well known in the art. Smectite clays, while dispersible in water, are not dispersible in organic fluids. If the organic cation contains at least one fatty acid group with preferably 10 or more carbon atoms, such "reaction-product" organoclays have the ability of dispersing into, and modifying the viscosity of, organic liquids. Such organoclays, over the last fifty years, have found an ever-increasing market imparting thickening or rheological properties to an increasingly wide number of such systems, including paints, inks, coatings, adhesives, drilling fluids and similar fluids.
Representative U.S. Pat. No. 4,664,820, issued to the assignee hereof, describes the preparation of organophilic clays, some of which have become commercial products, that are used to thicken organic systems. Such organoclays may function to thicken both polar or non-polar solvents, depending on the substitutents on the organic cation. For purposes of this patent, organic and solvent are used to mean essentially the same thing. Dr. J. W. ("Spike") Jordan, a new retired senior scientist employed by the assignee hereof, in "Proceedings of the 10th National Conference on Clays and Clay Minerals" (1963), discusses a wide range of applications, as then known, of such organoclays from high polarity organic liquids to low polarity solvent liquids.
Organophilic clay gellants have been developed since 1963 which are the reaction products of smectite-type clays with certain organic cations or mixtures of organic cations, and organic anions or anion combinations. These organoclays have the advantage of being easily dispersible in particular types of organic and solvent compositions without the need for a dispersion aids or polar activators under normal factory dispersion conditions. Illustrative patents which describe such improved organophilic clays are U.S. Pat. Nos. 4,105,578; 4,208,218; 4,412,018; 4,450,095; and 4,517,112.
More recent U.S. patents issued to assignee hereof show various uses of organoclays and processing improvements in making such organoclays using conventional quatemized, nitrile-derived ammonium compounds. These patents include U.S. Pat. Nos. 5,034,136; 5,075,033; and 5,151,155. See also U.S. Pat. No. 5,336,647 and U.S. Pat. No. 5,429,999. U.S. Pat. No. 5,336,647 in some length details the constituents of specific quaternary compounds useful in making commercial organoclays known as of its filing date.
Some of the problems of use, dispersibility and reduction of gloss associated with solid particulate types of thickeners such as organoclays and silica are overcome with the use of polyamide rheological additives. For example, U.S. Pat. No. 4,778,843 describes a polyamide rheological additive especially designed for organic solvent-based compositions, which comprises the reaction product of polycarboxylic acid, an active hydrogen compound of a specified carbon chain length and structure, and a monocarboxylic acid capping agent, wherein the additive exhibits excellent efficiency and dispersibility and is effective when predispersed in an organic solvent. Recent U.S. Pat. No. 5,349,011 to the assignee hereof describes a polyamide-ester rheological additive, especially for organic solvent-based compositions, which comprises the reaction product of polycarboxylic acid, an active hydrogen composition of a specified structure, an alkoxylated polyol, and a monocarboxylic acid capping agent. Said additive exhibits excellent efficiency and ease of dispersibility for aliphatic solvent-based coating compositions, and is effective when dispersed into a solvent.
U.S. Pat. No. 5,034,444 describes an anti-sag additive for non-aqueous coating compositions which is the reaction product of an alkoxylated aliphatic nitrogen-containing compound, an aliphatic diamine or mixtures thereof, and an organic polycarboxylic anhydride or acid, an alkanediol polyepoxide ether or mixtures thereof. The additive provides excellent anti-sag and storage stability properties, particularly for high solids coating compositions, without causing a significant increase in viscosity.